Director of National Intelligence James Clapper said in a new U.S. intelligence estimate delivered to the Senate today that al Qaeda’s ability to carry out major attacks have been seriously degraded as the result of “robust” U.S. counterterrorism efforts. The deaths of Osama bin Laden and other top al Qaeda leaders has “lead us to assess that core al Qaida’s ability to perform a variety of functions — including preserving leadership and conducting external operations — has weakened significantly,” Clapper said. The director also said that Iran is keeping the option open to develop a nuclear weapon but U.S. intelligence does not know if it will decide to build one.